==== Goal
//As a user, I need to block sock accounts from the CheckUser interface so I can prevent spread of vandalism on the wiki.//
This feature is to bring the existing block feature in CheckUser to the new CheckUser version.
==== Acceptance criteria
* There is a `Block` button next to the usernames on the top:
{F31702415, width=500}
* Clicking the `Block` button opens a section in the blue box with a `TagMultiselectWidget`. It should be prefilled with all the users that haven't been filtered out, in the order that they're showing up in the text above. The auto-complete should only work for users in that investigation (including the filtered out ones)
{F31742370,width=500}
* After a user selects users, IPs and clicks the `Continue` button, it takes them to the //Special:Investigate block// page (see {T248528}) with the "Usernames and IP addresses" input pre-filled with the usernames and IPs selected by the user.
* The //Special:Investigate block// will retain the context of the investigation: The multi-select widget will autocomplete for all users that were in the investigation, even those that weren't selected in the popup.